Resins, in particular hydrocarbon resins, are additives which have been known for a long time for rubber mixtures for treads of vehicle pneumatic tires. They serve above all as processing auxiliaries and cause the necessary green tack of the rubber mixtures. Furthermore, certain vulkanizate properties, such as hardness, modulus and swelling properties, can be influenced by resins. They can also be employed as vulcanization resins or adhesion promoters. Typical bonding resins employed in the rubber industry are e.g. petroleum resins, terpene resins, colophony resins, phenol-formaldehyde resins and coumarone-indene resins. Aliphatic resins from monomers of the C5 crude oil fraction or C5-containing copolymers are known as additives for rubber mixtures.
WO 2006/061064 A1 thus describes the use of from 5 to 35 phr of a C5/vinylaromatic copolymer in combination with 5 to 35 phr of MES or TDAE oil in a rubber mixture, wherein a rubber mixture with a polymer blend comprising styrene/butadiene rubber and butadiene rubber is disclosed.
EP 1707595 B1 discloses a rubber mixture for a side reinforcing layer or a bed apex which comprises 1 to 20 phr of a C5-based petroleum resin.
EP 0978533 B1 discloses a rubber mixture which comprises 21.5 phr of a hydrocarbon resin from 2-methyl-2-butene and 1,3-pentadiene and dicyclopentadiene in combination with 100 phr of styrene/butadiene rubber.
However, in the prior art limits are imposed on the use of relatively large amounts of resin due to the limited solubility in the polymer system of the particular rubber mixture.